You will LOVE this exercise, because it is the use of the INFINITIVE after any PREPOSITION. Just memorize: "Preposition + Infinitive."

Prepositions Common ly Used Before Infinitives:
a = to, at
al + inf = upon
antes de = before
con = with (sometimes "to" or "of")
de = of
después de = after
en = in, on, of
en lugar de = instead of
en vez de = instead of
hasta = until
sin = without